Abstract

Background

The presence of impaired glucose tolerance (IGT) and metabolic syndrome (MetS) are
two risk factors for Type 2 diabetes. The inter-relatedness of these factors among
adolescents is unclear.

Methods

We evaluated the sensitivity and specificity of MetS for identifying IGT in an unselected
group of adolescents undergoing oral glucose tolerance tests (OGTT) in the National
Health and Nutrition Evaluation Survey 1999–2010. We characterized IGT as a 2-hour
glucose ≥140 mg/dL and MetS using ATP-III-based criteria and a continuous sex- and
race/ethnicity-specific MetS Z-score at cut-offs of +1.0 and +0.75 standard deviations
(SD) above the mean.

Results

Among 1513 adolescents, IGT was present in 4.8%, while ATP-III-MetS was present in
7.9%. MetS performed poorly in identifying adolescents with IGT with a sensitivity/specificity
of 23.7%/92.9% for ATP-III-MetS, 23.6%/90.8% for the MetS Z-score at +1.0 SD and 35.8%/85.0
for the MetS Z-score at +0.75 SD. Sensitivity was higher (and specificity lower) but
was still overall poor among overweight/obese adolescents: 44.7%/83.0% for ATP-III-MetS,
43.1%/77.1% for the MetS Z-score at +1.0 SD and 64.3%/64.3% for MetS Z-score at +0.75
SD.

Conclusion

This lack of overlap between MetS and IGT may indicate that assessment of MetS is
not likely to be a good indicator of which adolescents to screen using OGTT. These
data further underscore the importance of other potential contributors to IGT, including
Type 1 diabetes and genetic causes of poor beta-cell function. Practitioners should
keep these potential causes of IGT in mind, even when evaluating obese adolescents
with IGT.